Fleming grew Penicillium in broth, removed the Penicillium, and poured the broth into culture dishes containing bacteria to see if the broth would kill the bacteria. What step in the scientific method does this represent?

Testing a hypothesis by experiment.

Explanation:

Hypothesis is a proposed explanation for scientific observations. And what's really important about a hypothesis is that, when written correctly, it helps create a well-designed experiment.

The two go together like peanut butter and jelly, movies and popcorn, and rock and roll. They not only complement one another but are also specific to each other. This is because an experiment is specifically designed to test a given hypothesis. Experiments are certainly fun to perform, but that's just a bonus for us! Their main purpose is to see whether our predictive statements, our hypotheses, are supported or not.

But even with a solid hypothesis, designing an experiment isn't always easy because there's a lot to take into consideration. So, let's take a look at the process to see how we would go about setting up our experiment based on what we're trying to test.